1. Field of the Invention
The present invention relates generally to fiber optic connectors, and more particularly, to a connectorized silicon bench and stepped ferrule that aids in the passive alignment of optical fibers and optical components on the bench.
2. Description of the Related Art
With the ever increasing popularity of the Internet and other data networks, fiber optics have become more and more prevalent. Since fiber has the capability of transmitting significantly more data than copper wires or wireless networks, a significant majority of the new networking infrastructure currently being implemented is based on fiber optics.
Fiber optic networks can generally be characterized as either “long” haul or “short” haul. Long haul networks are used to transmit data over long distances, such as between major metropolitan areas, across continents or oceans. Long haul networks typically rely on single mode fibers that are capable of transmitting only a single data stream of information. These cables are typically between 125 microns in diameter and have a single fiber optic inner core of approximately 8 microns. In contrast, short haul networks can are typically “multi-mode. Multi-mode cables typically have an outer diameter of approximately 125 microns and an inner fiber optic core of approximately 50 microns.
While much of the communications infrastructure being built to day is based on fiber optics, most computing environments still operate in the electrical domain. As a consequence, data signals have to be converted from the electrical to the optical domain, and vice versa, at equipment interfaces. Individual fiber cables therefore terminate at the junction at either an optical receiver, such as a photo-detector, that converts light pulses received over the fiber into electrical signals or an optical emitter, like a laser or LED, that converted electrical signals into light pulses and transmits them down the fiber.
A connector is typically used to connect the fiber with the optical detector or emitting source (hereafter sometimes generically referred to as “optical component”). A connection is typically made by including a lens that is positioned between the optical component and the end of the fiber. During data transmission, as the light pulses exit an emitter, the light tends to diverge. The lens converges the light to focus it on the cross section of the termination point of the fiber. During data receipt, the opposite occurs. The lens focuses or converges the diverged light exiting the fiber onto the optically sensitive surface of the photo-detector.
Since data transmission takes place in the form of light pulses traveling through a thread of glass, it is important that the optical component, lens and optical fiber are all in proper alignment. Ideally, tolerances should be within a few microns. To achieve these tolerances, active alignment is needed. With active alignment, the optical component and lens are first mounted onto the substrate. The fiber is next placed on the substrate. Light is then transmitted through the fiber while a robot positions the substrate relative to the fiber. At the point where the highest intensity of light from the fiber is measured, the assembly is considered “aligned”. The fiber is then locked into place on the substrate to maintain the alignment. A problem with the aforementioned package is that fiber attach results in a fiber “pigtail” which extends from the substrate. A ferrule connected to the pigtail is required to terminate the pigtail and to connect the fiber to an optical network or link. Traditional packages such as ‘butterfly’ packages thus require connectorization separate to the optical package itself.
Fibers can also be aligned to emitting and receiving components using a silicon optical bench which provides accurate mechanical alignment to approximately plus or minus one micron, but the assembly typically requires a package resulting in a fiber cable pigtail. A ferrule of some type is traditionally still needed to terminate the pigtail and enable connection to the main fiber link.
A ferrule that is integrated directly onto a silicon optical bench and that enables a direct optical connection interface to the silicon optical bench without the intermediate pig-tail fiber is therefore needed.